1. Field of the Invention
The invention in general relates to electronic probe adapters, and more particularly to a probe adapter that adjusts to fit a variety of integrated circuit chips.
2. Statement of the Problem
To test electronic parts, such as integrated circuits, an electronic probe must be electrically connected to their leads. One common way of making the electrical connection is by manual probing. In manual probing the user holds a narrow-tipped electronic probe by hand and attempts to put the tip of the probe on the lead which carries the signal to be examined. As leads have become narrower and the spaces between them very small, holding a single point probe by hand accurately and steady enough to make an electronic measurement has become difficult. With current surface mount technology having leads less than 0.01 inches wide and having a pitch of less than 0.05 inches, manual probing is nearly impossible.
One solution to the problem of manual probing of fine pitch surface mount components has been to develop a probe adapter for each surface mount component package on the market. That is, an adapter is created which is of the precise size and shape to receive the leads of a specific integrated circuit package, and which provides terminals electrically connected to each lead, which terminals are relatively widely spaced and accessible to a probe. These package-specific adapters work well, but a user that is not able to anticipate the specific surface mount package that he or she will need to probe either has to wait days, weeks, or even months while the appropriate adapter is ordered and delivered, devise a jury-rigged adapter, or must resort to manual methods. A user could take the approach of purchasing every adapter he or she is likely to need. However, since a single adapter can cost $200 or more, this can become expensive. This solution also can be confusing to use, and bulky to carry for remote applications.
Another solution has been the use of a miniature hook or set of hooks which wrap around a lead and can be pulled up tight to make electrical contact. This solution was originally designed for through-hole components, but has been extended to other leads, particularly in emergencies. However, the requirement of hooking and wrapping around each lead has also become difficult as pitches of leads on chips has become finer. Typically the spaces for the probe to hook and wrap around a lead are less than 0.015 inches on fine pitch surface mount components. This small gap requires the hook material to be thin and fragile. Further, there is a danger of shorting the lead to be tested to the adjacent lead.
Another method that is not commercially sold but is certainly practiced is to solder a conductor to the lead or trace to be tested, then hook an existing probe to the soldered-in conductor. This procedure requires a soldering iron to be available and is very time consuming. Further, soldering near fine pitch surface mount components is risky since leads can be unknowingly shorted together.
None of the solutions to connecting to fine pitch leads is satisfactory for the typical electronics specialist who must routinely test a variety of electronic components. Thus there is a need for a fine pitch probe adapter that permits accurate, reliable, and quick connection of a probe to a wide variety of integrated circuit components having fine pitch leads.
3. Solution to the Problem
The invention solves the above problems by providing a probe adapter that adjusts to many, if not all, surface mount integrated circuit packages as well as many other integrated circuit devices.
The invention provides an adapter that easily connects the leads on an integrated circuit package of any width to a set of connecting terminals to which a probe is easily attached. The connections are made via an elastomer pad in which thousands of tiny wires are embedded.
The invention provides a device for clamping the elastomer pad between the leads of the electronic device and a set of contacts that connect to the connecting terminals. The set of contacts is preferably a set of exposed traces on one end a flex circuit. The other end of the flex circuit extends from the clamping device and contains the connecting terminals. The flex circuit is chosen so the exposed traces have the same pitch as the leads on the electronic device. Flex circuits of different pitches may be inserted into the clamping device.
The clamping device is preferably a vise-like framework having a pair of jaws that are screwed, ratcheted, or otherwise urged toward each other to clamp the adapter to the electronic device. Each of the jaws has one or more teeth that fit in the gaps between the leads of the electronic device to align the exposed traces on the flex circuit with the leads. The teeth are tapered so that as the jaws are urged toward each other, the teeth self-align between the leads, thereby aligning the exposed traces and the leads.
Each of the jaws has a pocket for locating and holding the elastomer so that as the adapter is clamped to the electronic device, the elastomer is compressed and the wires embedded in it make contact between the leads and the contacts of the flex circuit.
As indicated above, each of the contacts of the flex circuit connects to an electrical terminal. The terminals are preferably conductive through-holes into which the pin of a probe may be inserted, but may be any suitable connector.
The probe adapter is used by opening the jaws wider than the fine pitch electronic device to be tested. The jaws are aligned over the leads to be tested, with the teeth roughly in gaps between the leads, then forced toward each other to urge the teeth into the gaps between the leads and compress the wire-containing elastomer between the leads and the flex circuit contacts. When the adapter is clamped to the electronic device, a test instrument probe is connected to the terminals of the flex circuit.